Messages in this thread | | | Date | Tue, 1 May 2012 17:20:52 +1000 | Subject | Re: [RFC] propagate gfp_t to page table alloc functions | From | Nick Piggin <> |
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On 25 April 2012 07:30, Andrew Morton <akpm@linux-foundation.org> wrote: > On Tue, 24 Apr 2012 17:48:29 +1000 > Nick Piggin <npiggin@gmail.com> wrote: > >> > Hmm, there are several places to use GFP_NOIO and GFP_NOFS even, GFP_ATOMIC. >> > I believe it's not trivial now. >> >> They're all buggy then. Unfortunately not through any real fault of their own. > > There are gruesome problems in block/blk-throttle.c (thread "mempool, > percpu, blkcg: fix percpu stat allocation and remove stats_lock"). It > wants to do an alloc_percpu()->vmalloc() from the IO submission path, > under GFP_NOIO.
Yeah, that sucks. CFQ has something similar.
Should just allocate it up front when creating a throttled group. Allocate and init when it first gets used schemes are usually pretty problematic. Is it *really* warranted to do it lazily like this?
> Changing vmalloc() to take a gfp_t does make lots of sense, although I > worry a bit about making vmalloc() easier to use! > > I do wonder whether the whole scheme of explicitly passing a gfp_t was > a mistake and that the allocation context should be part of the task > context. ie: pass the allocation mode via *current. As a handy > side-effect that would probably save quite some code where functions > are receiving a gfp_t arg then simply passing it on to the next > callee.
Both paragraphs make a lot of sense. Conceptually. :) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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